It's not so much the huge rainfall totals, although the numbers are definitely stacking up. What's remarkable about the current rainy spell in Brisbane is the relentlessness of the soaking.

Since rain started falling early on Sunday morning, it basically hasn't stopped for more than half an hour here or there, and nor does it look like stopping for at least another day. The rain has not been exceptionally heavy, but it has certainly been persistent.

If you look at the three-hour loop below, you'll notice something interesting. No, you're not seeing things. Showers on the radar are definitely drenching the city concurrently from two directions.

As Weatherzone meteorologist Joel Pippard explains, the main feed of moisture is being caused by a low level trough with onshore winds blowing in from the east.

There is also an upper trough above Queensland around 5.5 km up in the atmosphere with a feed of tropical moisture all the way from northern WA.

But as mentioned, the coastal trough is the main influence on the weather in southeast Queensland this Tuesday, and with sea surface temperatures generally at their peak in March, the level of precipitable moisture is enhanced at this time of year in systems like this.

• As we write this story at 3:30 pm AEST, Brisbane had recorded 19.2 mm since 9 am.
• That’s after 31.2 mm in the 24 hours to 9 am Tuesday, and 6.4 to 9 am in the 24 hours to 9 am Monday.

Meanwhile it's interesting to compare Brisbane with three of the southern capitals in recent months.

While Perth, Adelaide and Darwin have all been parched for at least the last two months – and indeed earlier this Tuesday today we wrote that Melbourne is likely to notch up its driest March in 170 years of records – Brisbane has been wet in recent months, as the graph below shows.

Brisbane's rainfall total should come very close to equalling or even exceeding the March average of 132.1 mm by the end of this event.

The good news is that the steady rain should ease in time for the Easter break from Friday through to Monday, although there is still the chance of showers on each of the four days.